eli5 if my monitor is 1080p why does 4k look better than 1080p videos?

Question

shouldn’t 1080p and 4k have no difference if my monitor is only capable of displaying 1080p

In: 422

Answer 1

I have a MacBook with a resolution of 2560×1600 so it’s native resolution for 16:9 videos is 1440p. On YouTube, is it better to select 4k or just use 1440p to save bandwidth?